By Geoff Norcross
http://stream.publicbroadcasting.net/production/mp3/knau/local-knau-683777.mp3
Flagstaff, AZ – The scientific community generally agrees that the Grand Canyon is about 6 million years old. New research shows that at least part of the canyon is much older.
It's the western end of the canyon, the part that follows that last hundred river miles, that's older. Researchers from the University of New Mexico say the western canyon started forming about 17 million years ago. It was part of a drainage system that pre-dated the formation of the complete Colorado River, which started cutting the eastern portion of the canyon much later. Eventually, the two canyons became one. Victor Polyak is a researcher with the university's Department of Earth and Planetary Sciences. He says his team's findings could change the course of research in the Grand Canyon.
POLYAK: You know our research is going to leave questions and people are going to pursue answers to those questions. So our research is a step forward in the study of the Grand Canyon.
Polyak's team dated the two ends of the canyon by exploring their caves. Deposits in cliffside caves are shielded from the effects of erosion, and gave the team a more accurate measuring tool than the exposed rock. Polyak points out the rock in the western canyon is smoother, which means it was worked over by gravity and wind for much longer.
The research findings can be found in the journal Science.